ASTM A182 F22 / P22 – 2¼Cr-1Mo steel: standards, composition and properties
2¼Cr-1Mo is the most used chromium-molybdenum steel for high temperature and hydrogen service. The same composition gets different names depending on the product form: F22 for forgings, Gr 22 for plate, P22 and T22 for pipe and tube, WP22 for fittings and WC9 for castings. This page gathers all the standards, classes and treatments of the family.
One composition, several standards
The name changes with the product form. When specifying, cite the standard, grade and class.
| Form | ASTM/ASME | Grade/class | EN | ABNT/others |
|---|---|---|---|---|
| Forging | A182 / SA-182 | F22 Cl.1, F22 Cl.3 | EN 10222-2 11CrMo9-10 (1.7383) | JIS G3203 SFVA F22* |
| Large forging | A336 / SA-336 | F22 Cl.1, F22 Cl.3 | EN 10222-2 11CrMo9-10 | — |
| Quenched forging | A508 / SA-508 | Gr 22 Cl.3 (also Cl.4, 5, 6 and 7) | — | Formerly A541 Gr 22 (withdrawn) |
| Plate | A387 / SA-387 | Gr 22 Cl.1, Gr 22 Cl.2, Gr 22L | EN 10028-2 10CrMo9-10 (1.7380) | JIS G4109 SCMV4-1, SCMV4-2 |
| Pipe | A335 / SA-335 | P22 | EN 10216-2 10CrMo9-10 | JIS G3458 STPA24 |
| Boiler tube | A213 / SA-213 | T22 | EN 10216-2 10CrMo9-10 | JIS G3462 STBA24 |
| Bar | A739 | B22 | — | — |
| Butt-weld fittings | A234 / SA-234 | WP22 Cl.1, WP22 Cl.3 | — | — |
| Casting | A217 / SA-217 | WC9 | EN 10213 G17CrMo9-10 (1.7379) | JIS G5151 SCPH32* |
| H₂S service | NACE MR0175 / ISO 15156-2 | hardness ≤ 22 HRC | — | Reactor requirements: API RP 934-A |
ASTM A541 was withdrawn and its grades, including Gr 22, were transferred to A508. "F22" alone does not define the strength: cite standard, grade and class.
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7228.40.00 | 7228.40 | 7228.40.0000 | 7228 40 90 |
| Hot-rolled bar | 7228.30.00* | 7228.30 | 7228.30.8041 | 7228 30 61 |
| Plate (> 10 mm, width ≥ 600 mm) | 7225.40.90* | 7225.40 | 7225.40.3050 | 7225 40 40 |
| Seamless pipe | 7304.19.00 | 7304.19 | 7304.19.5050 | 7304 19 10 |
| Welded pipe | 7306.19.00 | 7306.19 | 7306.19.5150 | 7306 19 00 |
| Flange and fitting | 7307.91.00 | 7307.91 | 7307.91.5030 | 7307 91 00 |
Class in Dustre's NCM table (INF 004): alloy steel.
Pipe: 7304.19 and 7306.19 are line pipe for oil and gas pipelines; boiler, heat exchanger or process tubes go under 7304.39/7304.59 (seamless) and 7306.30/7306.50 (welded).
*: US and EU codes are for reference; confirm with your customs broker. NCM codes with * were checked by Dustre against the current NCM, outside the INF 004 table. HS = first 6 digits of the NCM.
Chemical composition by standard (%)
The ranges of each standard side by side, to see where they differ.
| Standard | C | Mn | P max | S max | Si max | Cr | Mo | Others |
|---|---|---|---|---|---|---|---|---|
| A182 F22 | 0.05–0.15 | 0.30–0.60 | 0.040 | 0.040 | 0.50 | 2.00–2.50 | 0.87–1.13 | — |
| A387 Gr 22 | 0.05–0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.50 | 2.00–2.50 | 0.90–1.10 | Gr 22L: C ≤ 0.10 |
| A335 P22 / A213 T22 | 0.05–0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.50 | 1.90–2.60 | 0.87–1.13 | — |
| A234 WP22 | 0.05–0.15 | 0.30–0.60 | 0.040 | 0.040 | 0.50 | 1.90–2.60* | 0.87–1.13 | — |
| A217 WC9 | 0.05–0.18 | 0.40–0.70 | 0.04* | 0.045* | 0.60 | 2.00–2.75 | 0.90–1.20 | Cu ≤ 0.50; Ni ≤ 0.50; W ≤ 0.10; total ≤ 1.00 |
| EN 10028-2 10CrMo9-10 | 0.08–0.14 | 0.40–0.80 | 0.020 | 0.010 | 0.50 | 2.00–2.50 | 0.90–1.10 | Cu ≤ 0.30 |
| EN 10222-2 11CrMo9-10 | 0.08–0.15 | 0.40–0.80 | 0.025 | 0.015* | 0.50 | 2.00–2.50 | 0.90–1.10 | Ni ≤ 0.30; Cu ≤ 0.30 |
Mechanical properties by standard
Minimum values at room temperature, in the stated delivery condition.
| Standard and class | YS min | UTS | Elong. | RA | Hardness |
|---|---|---|---|---|---|
| FORGINGS | |||||
| A182 F22 Cl.1 | 205 MPa | ≥ 415 MPa | 20 % | 35 % | ≤ 170 HBW |
| A182 F22 Cl.3 | 310 MPa | ≥ 515 MPa | 20 % | 30 % | 156–207 HBW |
| A336 F22 Cl.1 | 205 MPa | 415–585 MPa | 20 % | 35 %* | — |
| A336 F22 Cl.3 | 310 MPa | 515–690 MPa | 18 % | 45 %* | — |
| A508 Gr 22 Cl.3 | 380 MPa | 585–760 MPa | 18 % | 45 %* | — |
| ROLLED | |||||
| A387 Gr 22 Cl.1 | 205 MPa | 415–585 MPa | 18 % | 40 % | — |
| A387 Gr 22 Cl.2 | 310 MPa | 515–690 MPa | 18 % | 40 % | — |
| EN 10028-2 10CrMo9-10 (≤ 16 mm) | 310 MPa | 480–630 MPa | 18 % | — | — |
| A335 P22 | 205 MPa | ≥ 415 MPa | 30 % long. / 20 % transv. | — | — |
| A213 T22 | 205 MPa | ≥ 415 MPa | 30 % | — | ≤ 163 HBW |
| EN 10216-2 10CrMo9-10 (≤ 40 mm) | 280 MPa | 480–630 MPa | 22 % long. | — | — |
| A739 B22 | 310 MPa | 515–655 MPa | 18 % | — | — |
| FITTINGS AND CASTINGS | |||||
| A234 WP22 Cl.1 | 205 MPa | 415–585 MPa | 20 %* | — | ≤ 197 HBW |
| A234 WP22 Cl.3 | 310 MPa | 520–690 MPa | 20 %* | — | ≤ 197 HBW |
| A217 WC9 | 275 MPa | 485–655 MPa | 20 % | 35 % | — |
| EN 10213 G17CrMo9-10 +QT | 400 MPa | 590–740 MPa | 18 % | — | — |
Class 1, Class 2 and Class 3: what changes
The composition is the same. The class defines the strength level obtained by heat treatment. Class 1 is annealed or normalized and tempered, with a minimum yield strength of 205 MPa. Class 3 of forgings and fittings, and Class 2 of plate, reach 310 MPa and are the most specified in steam and refinery projects. In A508, Classes 3, 4 and 5 are quenched and have even higher strength.
Heat treatments required by the standards
| Standard | Delivery condition | Minimum tempering |
|---|---|---|
| A182 F22 | Annealed, normalized and tempered, or quenched and tempered (austenitizing ≥ 900 °C) | 675 °C |
| A336 F22 | Normalized or liquid quenched, followed by tempering | 675 °C |
| A508 Gr 22 | Quenched (spray or immersion) and tempered, min. 0.5 h per inch | 650 °C |
| A387 Gr 22 | Annealed or normalized and tempered; quenched and tempered by agreement | 675 °C* |
| A335 P22 / A213 T22 | Full or isothermal anneal, or normalized and tempered | 675 °C |
| A234 WP22 | Annealed, isothermally annealed or normalized and tempered | 675 °C |
| A739 B22 | Normalized (927–982 °C) and tempered | 677 °C |
| A217 WC9 | Normalized and tempered, or quenched and tempered | 675 °C* |
| EN 10222-2 / 10028-2 | +NT (normalized and tempered) or +QT (quenched and tempered) | 650–750 °C |
| JIS STPA24 / STBA24 | Annealing or normalizing, followed by tempering | 650 °C |
Variants in the family
| Variant | Standards | Difference | YS / UTS |
|---|---|---|---|
| 2¼Cr-1Mo-¼V (F22V, UNS K31835) | A182 F22V, A336 F22V, A508 Gr 22V, A542 Type D Cl.4a, A832 22V | V 0.25–0.35 %, C 0.11–0.15 %, controlled residuals; standard for modern reactors | 415 / 585–760 MPa |
| 3Cr-1Mo (F21, UNS K31545) | A182 F21, A336 F21, A387 Gr 21, A335 P21 | Cr 2.70–3.30 %; little used today | 310 / ≥ 515 MPa |
| Modified F22 (API 6A 75K) | API 6A, based on A182 F22 | Adjusted chemistry and quench and temper up to class 75K; not an ASTM grade | 517 / ≥ 655 MPa |
| A387 Gr 22L | A387 | Carbon ≤ 0.10 % for weldability and toughness | per class |
Service temperature and hydrogen
- Continuous use: up to about 565–595 °C; ASME II-D tabulates stresses up to 649 °C, but above 595 °C oxidation limits it.
- Creep: starts to govern the design from about 425–480 °C.
- Hydrogen (HTHA): on the Nelson curve (API RP 941), 2¼Cr-1Mo sits well above C-½Mo and 1¼Cr-½Mo; the vanadium version goes further.
- Graphitization: does not occur: chromium stabilizes the carbides.
- H₂S (NACE MR0175 / ISO 15156): accepted with hardness ≤ 22 HRC, including in the weld.
Temper embrittlement
- Mechanism: in long service between about 370 and 565 °C, P, Sn, Sb and As segregate to the grain boundaries and raise the ductile-to-brittle transition temperature.
- J factor (Watanabe), base metal: J = (Si + Mn) × (P + Sn) × 10⁴, in wt. %; usual limit J ≤ 100.
- X̄ (Bruscato), weld metal: X̄ = (10P + 5Sb + 4Sn + As) / 100, in ppm; usual limit ≤ 15 ppm.
- Step cooling: accelerated aging with Charpy curves before and after; the criterion comes from the purchaser's specification (API RP 934-A).
Welding
| Item | Usual practice |
|---|---|
| Preheat | 150 to 250 °C |
| Consumables | AWS A5.5 E9018-B3 / E9015-B3 (electrode), A5.28 ER90S-B3 (TIG/MIG) |
| Post-weld heat treatment | Mandatory, about 690 to 750 °C |
| Hydrogen in the weld | Low-hydrogen consumables and post-heating to avoid cold cracking |
Filler metal for welding
The wire composition is usually not identical to the material: each page explains why.
International equivalents
| System | Designation |
|---|---|
| EN | 10CrMo9-10 (1.7380) plate and pipe · 11CrMo9-10 (1.7383) forging · G17CrMo9-10 (1.7379) casting |
| Old DIN | 10 CrMo 9 10 · GS-18 CrMo 9 10 |
| Old AFNOR | 10 CD 9.10 |
| JIS | SCMV4 (plate) · STPA24 (pipe) · STBA24 (boiler tube) |
| GB (China) | 12Cr2Mo1R (plate) · 12Cr2MoG (tube)* |
Equivalence is approximate: carbon, residuals and properties differ. Do not substitute one standard for another without a design review.
Typical applications
| Form | Where it is used |
|---|---|
| Forging | Flanges, nozzles and fittings for hydrotreating and hydrocracking reactors; forged rings and shells; steam and hydrogen flanges; F22 75K in API 6A wellheads |
| Plate | Shells and heads of pressure vessels and reactors, boiler drums, high-pressure separators |
| Pipe | P22: main and reheat steam, hydrogen lines · T22: superheaters, reheaters and exchangers |
| Fittings | WP22 elbows, tees, reducers and caps matching P22 pipe |
| Casting | Valve bodies and bonnets for steam and hydrogen, turbine and pump casings |
Frequently asked questions
Are F22 and P22 the same steel?
Yes, the same 2¼Cr-1Mo family. F22 is the forging (A182) and P22 is the pipe (A335). The pipe has a slightly wider chromium range (1.90–2.60 %).
What is the difference between F11, F22 and F91?
F11 (1¼Cr-½Mo) serves lower temperatures. F22 withstands more creep and hydrogen. F91 (9Cr-1Mo-V) has much higher creep strength and allows thinner walls, but requires stricter welding and heat treatment.
When to order F22V instead of F22?
In large hydroprocessing reactors, where the higher strength of F22V reduces thickness and improves hydrogen resistance.
Can F22 be used in H₂S service?
Yes, per NACE MR0175 / ISO 15156, as long as the hardness stays at 22 HRC or below, including in the weld.
